System for dispensing liquid carbon dioxide



J. c. HEssoN 2,848,879

2 Sheets-Sheet 1 /N VEA/TOR James 6I Hasso/7 m Aug. 26, 1958 SYSTEM FORDISPENSING LIQUID CARBON DIOXIDE Filed Aug. 17, 1955 SYSTEM FORDISPENSING LIQUID CARBON DIOXIDE Filed Aug. 17, 1955 J. C. HESSON Aug.26, 1958 2 Sheets-Sheet 2 Nx ff..

United States Patent @hice p 2,848,879 Patented Aug. 26, 1958 SYSTEM FORDISPENSING LIQUID CARBON DIOXIDE James C. Hessen, Riverdale, lll.,assignor to Cardox Cor4 poration, Chicago, Ill., a corporation ofillinois Application August 17, 1955, Serial No. 528,921

2 Claims. (Cl. 152-54) This invention relates to new and usefulimprovements in distribution systems for liquefied gases and deals moreparticularly with systems wherein liquid carbon dioxide is deliveredfrom storage at a low temperature and a correspondingly low pressure toa point of use where the vapor formed during delivery is separated fromthe liquid, returned to storage and reliqueed.

There is, in modern industry, an ever increasing use of liquid carbondioxide for purposes such as very low temperature refrigeration of coldtest boxes, the refrigeration of tumbling drums for removing ashmaterials from articles of molded rubber or the like, and other similarpurposes. For operations of this type, liquid carbon dioxide may bewithdrawn from a supply or storage tank through an insulated pipeline tothe point of use. Despite all normal precautions, however, thesurrounding air will cause a certainv amount of heat to be transferredto the carbon dioxide which will vaporize a portion of the liquid. Forexample, liquid carbon dioxide withdrawn from storage, at a temperatureof F., through a one-half inch pipe with a normal thickness ofinsulation, will evaporate at a rate of from ve to ten pounds of liquidfor each one hundred feet of pipeline. per hour when the temperature ofthe air is 80 F. Further, an increase in the thickness of the insulationwill increase its insulating value only in proportion to the naturallogarithm of the increased thickness and does not offer a practicalmethod for preventing the evaporation of some portion of the liquid.

Since the carbon dioxide vapor that is discharged with liquid carbondioxide at a point of use has very little cooling effect, the dischargedvapor may be considered to be almost a complete loss. In other words,the vapor will absorb very little heat whiley its temperature increasesthrough a substantial range as compared to the heat absorbed by theliquid during its evaporation at the point of use. Further, the combineddischarge of carbon dioxide vapor and liquid causes the discharge rateto be irregular and the sound of the escaping Vapor is disconcerting tothe workers in the vicinity of the operation.

lt is the primary object of this invention to provide a distributionsystem for low temperature liquid carbon dioxide which will eliminatethe delivery and loss of carbon dioxide vapor at the point of use andwill return the vapor to a refrigerated storage container.

A further important object of the invention is to provide a lowtemperature liquid carbon dioxide distribution system in which thevaporized carbon dioxide delivered with the liquid to a locationadjacent a discharge point is separated from the liquid, compressed andreliqueiied by its return to a refrigerated liquid storage container.

Still another important object of the invention is to provide a systemfor withdrawing low temperature liquid v carbon dioxide from storagevfor delivery to a point of use, the evaporatedportionof the carbondioxide reaching the point of use being separated from the liquidportion and returned to storage for reliquefaction.

Other objects and advantages of the invention will be apparent duringthe course of the following description.

In the accompanying drawings, forming a part of this specification andin which like reference characters kare employed to designate like partsthroughout the same,

Figure 1 is a schematic view of a low temperature, low pressure liquidcarbon dioxide distributing system embodying the invention, and

Figure 2 is a longitudinal sectional View of the iloat operated valveemployed in the system of Fig. 1.

In the drawings, wherein for the purpose of illustration is shown thepreferred embodiment of this invention, and first particularly referringto Fig. l, reference character 3 designates a supply or storagecontainer surrounded by suitable insulating material 4. The' container3`is charged with liquid carbon dioxide in any suitable manner and thetemperature of the liquid is maintained at approximately 0 F. `by thecoils 5 of a conventional mechanical refrigeration system, not shown. Atthis low temperature, the vapor pressure of the liquid carbon dioxidewill bemaintained at approximately three hundred and ten pounds persquare inch, gauge.

Leading from the bottom of the container 3 is a pipe 6 which provides aflow path for the liquid carbon dioxide 'withdrawn from the container.The pipe 6 is surrounded by suitable insulating material 7 to minimizethe absorption of heat by the cold liquid carbon dioxide and a manuallyoperated valve 8 is provided adjacent the container 3 to control theiiow of liquid through the pipe.

The pipe 6 leads from the container 3 to one or more points of use ofliquid carbon dioxide and at each of such points the pipe 6 is connectedto the inlet port 9 of a float valve 11 by an insulated branch pipe 12.During the flow of the liquid carbon dioxide from the container 3 to theiloat valve 11, through the pipe 6 and branch pipe 12, heat will beabsorbed by the very cold liquid and will convert a portion of theliquid to Vapor. Also, there will be a reduction in the pressure on theliquid due to the release of liquid from the system and this reductionin pressure will contribute to the conversion of a portion of the carbondioxide entering the iioat valve 11 to vapor. Since the carbon dioxidevapor has a very low heat absorbing capacity, the float valve 11 isprovided to separate the vapor from the liquid before the latter owsthrough the outlet 13 o'f the valve and through the insulated pipe 14 tothe point of use 15 for the liquid.

It is to be understood that the purpose for which the liquid carbondioxide is employed at the point of use 15 may be in connection with anyconventional lcooling operation and does not form a part of thisinvention. A manually operated valve 16 is provided for the pipe ladjacent the point of use 15 to control the discharge of the liquid.

Referring now to Fig. 2 for a detail description of the float valve 11and the manner in which it functions to separate the carbon dioxidevaporfrom the liquid flowing to the point of use 15, it will be notedthat the mixture of liquid and vapor flowing through the pipe 12 entersthe iioat chamber i7 through the inlet port 9 at the t'op of the valve.After entering the chamber 17, the liquid and vapor will separate andthe liquid will occupy the bottom portion ofthe chamber from which itmay iiow through the outlet port 13 into the pipe 14. The carbon throughthe latter.

, splines 21 Vwhich slidably engage the bore of the valve guide 22 tolimit movement of the Valve to an axial direction. At .the outer end ofthe valve 18 there is provided an apertured valve seat 23 and the valve18 is provided with a conical seating surface 24 which is movable intoengagement with the valve seat to close the aperture Movement of thevalve 18 away from the valve seat 23, on the other hand, will open theaperture through the `valve seat so that vapor may ow between thesplines 21 and through the valve seat to the vapor outlet port 19. Atthe inner end. of the valve 18 there is provided an operating stem 25which is threadedly connected to the valve 18.

Axial movement is imparted to the valve 18 to control the ow of vaporfrom the chamber 17 to the vapor outlet port 19 by an elongated oat 26which is positioned in the chamber 17 and is mounted for pivotalmovement about the pin 27 which lpasses through the block 28 that isrigidly. connected to the oat stem. One end portion of the block 28 ispivotally connected to the valve stem 25 by a pin 29 and the oppositeend portion of the block is provided with a lug 31 for engaging theadjustable stop 32 to limit the pivotal movement of the block about thepin 27. Of course, some lost motion must be provided at the pin 29 topermit pivotal movement of the block 28 to eiect the straight linemovement ofthe valve 18 in its guide 22.

It will be readily apparent that the'float 26 Will be raised and loweredin accordance With the level of the liquid in the bottom portion of thechamber 17 and such movement of the float will effect pivotal movementof the rigidly connected block 28 about the pin 27 to open and close thevalve 18. In other words, as the level of the liquid carbon dioxide inthe chamber 17 rises, the float 26 will be moved upwardly to effectpivotal movement of the block 28 in a clockwise direction, asillustrated in Fig. 2, and will cause the valve 18 Vto move toward thevalve seat 23 so that the seating surface 24 will close the aperturethrough the valve seat. The flow of vapor yfrom the upper portion of thechamber 17 to the outlet port 19 will thereupon stop and vapor willaccumulate in the upper portion of the chamber until the level of theliquid is lowered. No liquid, therefore, will be permitted to escapethrough the vapor outlet port 19. Conversely, when the level of theliquid carbon dioxide in' the chamber 17 drops, the float 26 will belowered and the block 28 will beppivoted in a counter clockwisedirection, as viewed in Fig. 2, to eiect ymovement of the valve 18 awayfrom the valve seat 23 so that vapor will be free to ow from the upperportion of the chambery 17 between the splines 21 of the valve andthrough the apertured valve seat 23 to the vapor outlet port 19. Thisdischarge of vapor from the chamber 17 will continue until the liquidlevel again rises by a suflicient amount to cause the float 26 toreclose the valve 18.

,Referring once again to Fig. l, it will be seen that the carbon dioxideVapor flowing from the oat valve V11 through the vapor outlet port 19will enter an insulated branch pipe 33 for iiow into the vapor returnpipe 34 which may oe connected to one or more branch pipes 33 dependingupon the number of points of use of liquid carbon dioxide. The branchpipe 33 and vapor return pipe 34 provide a flow path for the vapor fromthe oat valve l1 to the inlet port of a compressor 35 and a vaporaccumulator cylinder 36 is arranged in open communication with the pipe34 to increase the volume of the vapor yavailable for flow to thecompressor. A pressure operated electric switch 37 is also mounted inopen communication with the pipe 34 and may be adjusted, `for example,to close at a pressure of two hundred and seventy-ve pounds per squareinch, gauge, and to open at a pressure of, two hundred and twenty-fivepounds per square inch, gauge. The compressor 35 is driven by anelectric motor 38 which is connected in a circuit includ- '4 ing wires39 and 40 and the switch 37 so that the compressor will be operated whenthe switch is closed and will be stopped when the switch is opened.

The compressed carbon dioxide Vapor owing from the compressor 35 entersa pipe 41 and passes through two oil traps 42 into the upper portion ofthe container 3. The pressure of the vapor entering the container 3 fromthe pipe 41 is greater than the storage pressure of the liquid carbondioxide so that the 4compressed Vapor will be reconverted to liquid asits temperature is reduced by the refrigerator coils 5.

To summarize the operation of the system described above, liquid carbondioxide is withdrawn from the container 3 and flows through the pipe 6to a float valve 11, a portion of the liquid being evaporatedby theabsorption of heat during its ilow through the pipe. The oat valve v 11functions to separate the vapor from the liquid, the liquid beingpermitted to iiow to the point of use and the vapor being dischargedinto a returnV pipe 34. Vapor will accumuate in the return pipe 34 andthe accumulator cylinder 36 until the pressure therein reaches a valueof, for example, two hundred and seventy-live pounds per square inch,gauge, at which time the pressure operated switch 37 will close toactuate the motor 38 which drives the compressor 35. Vapor is thereuponwithdrawn from the pipe 34 and accumulator 36 and is compressed 'to apressure at which the vapor will flow through the pipe 41 into thecontainer 3 where it will be reliquefied at the storage temperature.When a suicient quantity of vapor has been withdrawn from the pipe 34and accumulator cylinder 36, the pressure operated switch 37 will openthe circuit to the motor 38 to stop the compressor 35 until additionalvapor has again accumulated in the pipe 34 and accumulator cylinder. Itwill be readily apparent thatV the system described above provides forthe discharge of liquid carbon dioxide to ay point of use 15, thedischarged liquid being substantially free of vapor and the evaporatedportion of the liquid being returned to a storage container 3 forreliquecation and subsequent use.

It is to be understood that the form of this invention herewith shownand described is to be taken as a pre.

'to a point of use, comprising an insulated chamber adjacent said pointof use for containing a supply of liquid carbon dioxide, said chamberhaving an inlet and a vapor outlet in the upper portion thereof, saidinlet and vapor outlet each being located above the level of the liquidcarbon dioxide normally contained in said chamber, means forming aninsulated iiow path from the bottom portion of said storage container tosaid chamber inlet, means forming an insulated ilow path from the bottomportion of said chamber to said point of use, iloat actuated valve meansfor opening and closing said vapor outlet in response to changes in theliquid level in said chamber to prevent the ow of liquid from said vaporoutlet and to release the vapor from said flow path, a compressor havingan inlet port, means forming a flow path from said vapor outlet to saidcompressor inlet port, means for controlling the actuation of saidcompressor in response to changes in the pressure in said last mentionedflow path, means for returning the compressed vapor from saidcompressorto said storage container, and means for lowering thetemperature of the vapor returned to said storage container to reliquefythe same and to maintain the low temperature and pressure of the liquidin the storage container.

2. Apparatus as deiined in claim l further characterized by accumulatormeans arranged in open communication fell with said vapor flow path tothe compressor to increase the volume of vapor available for flow tosaid compressor.

References Cited in the le of this patent ASA UNITED STATES PATENTS WadeNov. 19, 1935 Cantacuzene Mar. 31, 1942 Benz et a1. Aug. 4, 1942 FOREIGNPATENTS France July 19, 1927

